sane-usb - USB configuration tips for SANE
This manual page contains information on how to access scanners with a USB
interface. It focusses on two main topics: getting the scanner detected by the
operating system kernel and using it with SANE.
This page applies to USB most backends and scanners, as they use the generic
sanei_usb interface. However, there is one exceptions: USB Scanners supported
by the microtek2 backend need a special USB kernel driver, see
(5) for details.
This is a short HOWTO-like section. For the full details, read the following
sections. The goal of this section is to get the scanner detected by
Run sane-find-scanner. If it lists your scanner with the correct vendor and
product ids, you are done. See section SANE ISSUES
for details on how
to go on.
sane-find-scanner doesn't list your scanner? Does it work as root? If yes, there
is a permission issue. See the LIBUSB
section for details.
Nothing is found even as root? Check that your kernel supports USB and that
libusb is installed (see section LIBUSB
For accessing USB devices, the USB library libusb is used. There used to exist
another method to access USB devices: the kernel scanner driver. The kernel
scanner driver method is deprecated and shouldn't be used anymore. It may be
removed from SANE at any time. In Linux, the kernel scanner driver has been
removed in the 2.6.* kernel series. Only libusb access is documented in this
SANE can only use libusb 0.1.6 or newer. It needs to be installed at build-time.
Modern Linux distributions and other operating systems come with libusb.
Libusb can only access your scanner if it's not claimed by the kernel scanner
driver. If you want to use libusb, unload the kernel driver (e.g. rmmod
scanner under Linux) or disable the driver when compiling a new kernel. For
Linux, your kernel needs support for the USB filesystem (usbfs). For kernels
older than 2.4.19, replace "usbfs" with "usbdevfs" because
the name has changed. This filesystem must be mounted. That's done
automatically at boot time, if /etc/fstab contains a line like this:
none /proc/bus/usb usbfs defaults 0 0
The permissions for the device files used by libusb must be adjusted for user
access. Otherwise only root can use SANE devices. For Linux
devices are located in /proc/bus/usb/ or in /dev/bus/usb, if you use udev.
There are directories named e.g. "001" (the bus name) containing
files "001", "002" etc. (the device files). The right
device files can be found out by running scanimage -L as root. Setting
permissions with "chmod" is not permanent, however. They will be
reset after reboot or replugging the scanner.
Usually udev or for older distributions the hotplug utilities are used, which
support dynamic setting of access permissions. SANE comes with udev and
hotplug scripts in the directory tools/udev and tools/hotplug. They can be
used for setting permissions, see /usr/share/doc/libsane/README.linux,
tools/README and the README in the tools/hotplug directory for more details.
For the BSDs
, the device files used by libusb are named
. Use chmod to apply appropriate permissions.
This section assumes that your scanner is detected by sane-find-scanner. It
doesn't make sense to go on, if this is not the case. While sane-find-scanner
is able to detect any USB scanner, actual scanning will only work if the
scanner is supported by a SANE backend. Information on the level of support
can be found on the SANE webpage (http://www.sane-project.org/
the individual backend manpages.
Most backends can detect USB scanners automatically using "usb"
configuration file lines. This method allows one to identify scanners by the
USB vendor and product numbers. The syntax for specifying a scanner this way
usb VENDOR PRODUCT
is the USB vendor id, and PRODUCT
is the USB product
id of the scanner. Both ids are non-negative integer numbers in decimal or
hexadecimal format. The correct values for these fields can be found by
running sane-find-scanner, looking into the syslog (e.g., /var/log/messages)
or under Linux by issuing the command "cat /proc/bus/usb/devices".
This is an example of a config file line:
usb 0x055f 0x0006
would have the effect that all USB devices in the system with a vendor id of
0x55f and a product id of 0x0006 would be probed and recognized by the
If your scanner is not detected automatically, it may be necessary to edit the
appropriate backend configuration file before using SANE for the first time.
For a detailed description of each backend's configuration file, please refer
to the relevant backend manual page (e.g. sane-mustek_usb
(5) for Mustek
create a symlink from /dev/scanner
to the USB device
because this link is used by the SCSI backends. The scanner may be confused if
it receives SCSI commands.
- If the library was compiled with debug support enabled,
this environment variable controls the debug level for the USB I/O
subsystem. E.g., a value of 128 requests all debug output to be printed.
Smaller levels reduce verbosity. Values greater than 4 enable libusb
debugging (if available). Example: export SANE_DEBUG_SANEI_USB=4.
Henning Meier-Geinitz <email@example.com>